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Beacon Station No 641 December 8, 1997 Californiad i i l Suhslirface Investigation Repo cement/bentonite grout was used to complete the annular seal from the top of the seal to 6,( approximately one foot bsg The top of the well casing was secured with a locking water- tight expansion cap within a 24-inch diameter, water-tight, steel traffic-rated box previously installed over 18-inch PVC conductor casings The construction details are shown on the corresponding boring log in Appendix C Groundwater ni in 1l Deyel!2pment and Sampling On November 14, 1996, Horizon personnel conducted well development, purging and sampling of groundwater monitoring well M W-l On March 18, 1997, well MW-1 was sampled a second time On October 2, 1997, Horizon personnel conducted well development, purging and sampling of groundwater monitoring wells MW-2 through MW- 5 Depth to groundwater levels were taken before and after purging/sampling, and were recorded on Monitoring Well Data Sheets (Appendix D) and summarized in Table 2 Groundwater samples were contained in chilled storage for transport to the laboratory for the requested analyses Sparge Well Development On October 2, 1997, Horizon personnel conducted well development of sparge well SW-1 Depth to groundwater levels were taken before and after purging and were recorded on a Monitoring Well Data Sheet (Appendix D) The sparge well was not sampled Development was conducted to insure maximum well efficiency for future remedial air sparging Wellhea-d-Elevatiollurycy and !Groundwater Gradient On Novenber 6, 1997, Horizon personnel surveyed all the monitoring wells at the site ' relative to an elevation of 100 00 feet assigned to the north side of the top of the well casing of well MW-4 (Appendix E) The relative wellhead elevations are included with the well numbers on Table 2, along with the groundwater data collected from the wells during sampling events The groundwater flow direction for October 2, 1997 was calculated to be generally towards the east with an average magnitude of approximately 0 0088 foot/feet 1641-13 rpt 8 HORIZON ENVIRONMENTAL INC